Hi,
I was using mysql for my development for a long-long time. But I decided to try postgresql as I watched Ryan Bates screencast which showed the fullt text search capabilities of postgresql.
I was motivated to try postgresql since heroku added a new addon which enables any application to use the lastest(9.1.13) postgresql. And as a bonus the capacity of that DB is unlimited... However I can hardly believe that it will remain free forever...
So...
I created a new DB on my heroku account for my application and I followed the migration manual and voila. It took me about no more than 15 minutes to transition to a new DB.
It was a nice experience. :)